Computational systems biology has brought many new insights to cancer biology through the quantitative analysis of metabolic, gene regulatory and signaling networks. The goal of this project is to apply a systems biology approach to the understanding of iron metabolism in normal breast epithelium as it transitions to breast cancer. In recent years, much has been learned about iron metabolism, revealing a complex regulatory network with intertwined feedback loops. Proteins of iron metabolism exhibit substantial changes as epithelial cells undergo malignant transformation; further, intracellular labile iron contributes to the generation of reactive oxygen species, which have been implicated in the pathogenesis of breast cancer. However, intracellular iron metabolism has not yet benefited from a systems biology approach. The proposed project will test the hypothesis that iron is regulated differently in normal and malignant cells. This will be done by constructing predictive mathematical models of a core iron metabolism network in normal breast cells. These models will then be used to formulate hypotheses about changes in the network that occur as cells transition to a cancer phenotype. These hypotheses will then be tested experimentally. Carefully gathered time course data will be used to construct, validate, refine, and to test the predictive power of the models. Although normal and cancer cells exhibit substantial differences in proteins of iron metabolism, previous attempts to exploit these differences to therapeutic advantage have been largely empirical and disappointing. The project goal is to move beyond empiricism to a rational predictive model that will enable an understanding of basic forces that drive changes in iron metabolism during malignant progression. The ultimate aim is to use this approach not only to understand the role of iron in cancer formation, growth and metastasis, but to identify key nodal points that may represent new therapeutic targets in the future, a potentially very high impact on human health.